They also want to know about any talk on changing international security agreements, if Trump made any commitments tied to the United States' presence in Syria or military exercises for the North Atlantic Treaty Organization (NATO).
"Mr. President, the answers to these questions are of critical importance to U.S. national security. Answering them in full, without hesitation, will demonstrate that you do still hold America’s interests first," the Democratic senators wrote.
They added that Trump's "cursory description" of the meeting did not assuage their concerns and "we as a nation must now wonder exactly what you discussed and may have promised to President Putin."
Democrats also want to know if Trump pressed Putin on Russia's annexation of Crimea or for the extradition of the 12 Russian nationals indicted last week for meddling in the 2016 election.
The letter comes after Trump shocked Washington on Monday when he refused to condemn Russia's election meddling during a joint press conference with Putin. Trump tried to walk back his comments on Tuesday amid a political firestorm, saying he accepts the intelligence community's finding that Russia interfered in the election.
But muddling his message, Trump added that it "could be other people also."
The Senate is debating passing new sanctions legislation targeting Russia in the wake of the Helsinki summit and last week's indictment.
Democrats added on Tuesday that in addition to Secretary of State Mike PompeoMike PompeoSunday shows preview: Coronavirus dominates as country struggles with delta variant Christie, Pompeo named co-chairs of GOP redistricting group America needs a new strategy for Pacific Island Countries MORE, who is slated to testify before the Foreign Relations Committee next week, they also want U.S. ambassador to Russia Jon Huntsman, a high-ranking intelligence official and Defense Secretary Jim Mattis to testify.